Title: Developing Upscaling Approach for Swarming Hydraulic Fractures Observed at Hydraulic Fracturing Test Site through Multiscale Simulations

Abstract

We show that this work aims to address a challenge posed by recent observations of tightly spaced hydraulic fractures in core samples from the hydraulic fracturing test site (HFTS) in the Middle Wolfcamp Formation. Many fractures in retrieved cores have subfoot spacing, which is at odds with conventional models in which usually one hydraulic fracture is initiated per cluster. Models assuming a single fracture at each cluster, although a common practice, often predict excessive fracture propagation that is inconsistent with microseismic observation. Here, we aim to develop a numerical approach to effectively account for densely spaced hydraulic fractures in field-scale simulations. Because it is impractical to explicitly model all aforementioned fractures, we develop a new upscaling law that enables existing simulation tools to predict reservoir response to fracture swarms. The upscaling law is derived based on an energy equivalence argument and validated through multiscale simulations using a high-fidelity code, GEOS. The swarming fractures are first modeled with a spacing that is much smaller than the cluster spacing; these fractures are then approximated by an upscaled, single fracture based on the proposed upscaling law. The upscaled fracture is shown to successfully match the energy input rate and produce the total fracturemore » aperture and average propagation length of the explicitly simulated swarm. Afterward, the upscaling approach is further implemented in 3D field-scale simulations and validated against the HFTS microseismic data of a horizontal well. Our results show that hydraulic fracture swarming can significantly affect fracture propagation behaviors compared with the propagation of single fractures as assumed by conventional modeling approaches. Under the considered situations, the conventional treatment yields fast propagation speed that far exceeds that indicated by the microseismic data. We also illustrate that this discrepancy can be reduced readily through the implementation of the upscaling law. Our results demonstrate the importance of accounting for the fracture swarming effect in field-scale simulations and the efficacy of this approach to enable realistic predictions of reservoir responses to fracture swarms, without the need to model tightly spaced fractures individually.« less

Authors:

Fu, Wei ^[1]; Morris, Joseph P. ^[1]; Fu, Pengcheng ^[1]; Huang, Jixiang ^[1]; Sherman, Christopher S. ^[1]; Settgast, Randolph R. ^[1]; Ryerson, Frederick J. ^[1]

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+ Show Author Affiliations

1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Publication Date:

Fri Mar 12 00:00:00 EST 2021

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE Office of Fossil Energy (FE), Oil & Natural Gas

OSTI Identifier:

1860691

Report Number(s):

LLNL-JRNL-815344
Journal ID: ISSN 1086-055X; 1023115

Grant/Contract Number:  

AC52-07NA27344

Resource Type:

Accepted Manuscript

Journal Name:

SPE Journal

Additional Journal Information:

Journal Volume: 26; Journal Issue: 05; Journal ID: ISSN 1086-055X

Publisher:

Society of Petroleum Engineers (SPE)

Country of Publication:

United States

Language:

English

Subject:

02 PETROLEUM; scaling method; reservoir geomechanics; us government; hydraulic fracturing; fracturing materials; proppant; reservoir characterization; wellbore integrity; reservoir simulation; fracturing fluid; upscaling; swarm; closely space fractures; numerical simulation